docs: def _raw_pack(key_handle, flags, data):
      """
      Common code for packing payload to YHSM_HMAC_SHA1_GENERATE command.
      """
      # #define YHSM_HMAC_RESET          0x01    // Flag to indicate reset at first packet
      # #define YHSM_HMAC_FINAL          0x02    // Flag to indicate that the hash shall be calculated
      # typedef struct {
      #   uint32_t keyHandle;                 // Key handle
      #   uint8_t flags;                      // Flags
      #   uint8_t numBytes;                   // Number of bytes in data packet
      #   uint8_t data[YHSM_MAX_PKT_SIZE - 6]; // Data to be written
      # } YHSM_HMAC_SHA1_GENERATE_REQ;
      return struct.pack('<IBB', key_handle, flags, len(data)) + data